the racelands are like 2.5" so you dont have to worry much about fitment issues. just make sure you use correct gaskets, torque the bolts enough, etc and you should be fine.
if you have a leak it should be audible.
post some vids/dynos once you get them on!
catless downpipes are my favorite mod so far

Raceland has been discounting their pipes with poor welds and rust on the inside. They have just manufactured a batch that is suppose to be much better. If you have large beads on the inside of the welds.... send them back. They are great about taking them back right now. I have a buddy that ordered some that had the poor welds and rust and they took them back, no questions asked. He picked up a set of VK used for $250 and will end up with some of the best pipes available for just a few $ more. Pipes don't loose performance over time unless they have poor welds. I have heard of guys getting great sets of Raceland pipes also so If you get a good clean set you should be A O K!
See the link below for what to look for.....http://www.n54tech.com/forums/showthread.php?t=9706